/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.elasticsearch.cluster;

public enum MasterNodeChangePredicate implements ClusterStateObserver.ChangePredicate {
    INSTANCE;

    @Override
    public boolean apply(
        ClusterState previousState,
        ClusterState.ClusterStateStatus previousStatus,
        ClusterState newState,
        ClusterState.ClusterStateStatus newStatus) {
        // checking if the masterNodeId changed is insufficient as the
        // same master node might get re-elected after a disruption
        return newState.nodes().getMasterNodeId() != null && newState != previousState;
    }

    @Override
    public boolean apply(ClusterChangedEvent changedEvent) {
        return changedEvent.nodesDelta().masterNodeChanged();
    }
}
